A retail store desirably sells various commodities with the commodities displayed in a place where the commodities should be displayed. For example, underwear should not be mixed in a shelf where T-shirts should be displayed. However, some customer leaves a commodity, which the customer picks up to purchase, in a place where the commodity should not originally be displayed feeling it troublesome to return the commodity to its original place.
As an example of a technique for preventing a commodity from being left, JP-A-2005-352725 discloses a commodity movement identifying apparatus. The commodity movement identifying apparatus includes an RFID reader arranged in a commodity display shelf, an RFID reader attached to a shopping basket, and a notifying unit attached to the shopping basket. The RFID readers have a radio communication function. A customer carries the shopping basket during shopping. In the commodity movement identifying apparatus, the RFID readers read an identification code peculiar to each of commodities from an RFID tag attached to the commodity, whereby the commodity movement identifying apparatus grasps the present position of the commodity. When the customer is about to return a commodity to a place other than a place to which the commodity should originally be returned, the notifying unit urges the customer to return the commodity to the place to which the commodity should originally be returned. JP-A-2005-352725 also discloses that the commodity movement identifying apparatus causes a commodity-position-abnormality display unit to display position abnormality of a commodity in order to notify an administrator of a store of the position abnormality of the commodity when a customer returns the commodity to a wrong place. The commodity-position-abnormality display unit is connected to a communication network included in a store.
In the technique disclosed in JP-A-2005-352725, the notifying unit is attached to the shopping basket to urge a customer to return a commodity to its original position. However, when the customer is urged to take an action to return the commodity to its original position, a part of a purchasing action of the customer is limited. The limitation on the purchasing action prevents a purchasing behavior of the customer and deprives the customer of an opportunity of commodity purchase. Some customer holds a commodity, which the customer plans to purchase, by hand without carrying a shopping basket. The technique disclosed in JP-A-2005-352725 cannot urge the customer not carrying a shopping basket to return the commodity to its original position. In the technique disclosed in JP-A-2005-352725, RFID readers having the radio communication function and notifying units are attached to all shopping baskets prepared in the store. Therefore, initial cost in introducing this technique into the store is enormous.